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Bobcat L28 Troubleshooting

The Bobcat L28 small articulated loader is powered by Kubota D1305-E4B 4-cycle vertical 3-cylinder water-cooled diesel engine with a rated power of 24.7 hp (18.5 kW) at 2600 rpm. The Bobcat L28 is equipped with a hydrostatic transmission, power steering system, hydraulic disc brakes, and 23x8.50-12 or 26x12.00-12 tires. The hydraulic system has a pump with fluid flow rate of 12.1 gpm (45.8 lpm). The hydraulic pressure is 2900 psi (200 bar). The small wheel loader has a rated operating capacity of 1220 lbs (555 kg) and tipping load of 2440 lbs (1110 kg). The maximum lift height is 104.3" (2650 mm) to hinge pin, and bucket breakout force is 3090 lbs (1405 kg).

Engine Troubleshooting

Engine starts up hard or doesn't start
Air in fuel tank - Bleed fuel tank.
Fuel filter plugged - Filter maintenance required.
Clogged or defective injection nozzles - Change fuel injection nozzles.
Water or dirt in fuel system - Drain, flush, and service the system.
Excessive valve clearance - Adjustment procedure required.
Fuel injection pump is damaged - Replace or repair injection pump.

Diesel starts and then shuts off
Air filter is plugged - Clean or change.
Fuel filter element clogging - Clean or replace the filter.
Fuel injection pump has loose connections - Tighten the connections.
Fuel injectors are dirty or defective - Change or clean fuel injectors.
Fuel injection pump malfunctioning - Rebuild or change fuel pump.

Engine stalls while running
Engine is not warmed up to required temperature - Warm up the engine.
Fuel filter plugging - Change filter element.
Air in the fuel lines - Bleed the fuel lines.
Dirty or faulty injection nozzles - Inspect nozzles and replace if necessary.
Wrong setting of fuel injection pump timing - Set up as recommended.

Engine stops at low idle speed
Low idle speed setting is not correct - Adjust the low idle speed.
Fuel injection pump is not operating properly - Install a new pump or rebuild.
Fuel injector fault - Test and replace fuel injectors if necessary.
Valve out of adjustment - Adjustment procedure required.

Lack of engine power
Air filter is dirty - Replace or clean air filter element.
Clogged injection nozzle - Clean or change injection nozzles.
Fuel injection pressure is wrong - Adjust to correct pressure.
Valve out of adjustment - Check and adjust as required.
Low idle speed adjustment is incorrect - Adjustment required.
Restricted fuel lines or hoses - Clean fuel system lines and hoses.
Defective cylinder head gasket - Install new cylinder head gasket.
Worn or damaged piston rings - Replace the piston rings as required.

Engine overheated
Not enough coolant - Add coolant fluid to cooling system and also check it for leaks.
Low engine oil level - Checking oil level and add if necessary.
Radiator core is clogged or radiator cap is leaking - Clean radiator or change cap.
Fan belt is loose or defective - Fan belt must be replaced.
Diesel engine overloaded - Reduce load on the engine.

Oil pressure is low
Oil level is low - Fill crankcase to proper oil level.
Dirty oil filter element - Replace or service engine oil filter.
Incorrect oil viscosity - Drain and refill with oil of correct grade and viscosity.
Incorrect oil clearance in crankshaft bearing - Bearing needs to be changed.
Worn oil pump - Remove and inspect oil pump.

Engine noises or knocks
Low engine oil level - Check oil level and add oil as required.
Engine is not warmed up to required temperature - Normalize the temperature by warming up the engine.
Fuel injection pump timing is not adjusted - Set the fuel pump timing correctly.
Wrong adjustment of low idle speed - Test and adjust.
Fuel injectors are faulty or clogged - Inspect fuel injectors and change as required.
Connecting rod is defective or not aligned - Align or replace connecting rod.
Worn or scored pistons - Replace the pistons.

Hydrostatic Transmission Troubleshooting

Hydrostatic transmission is excessively noisy
Contaminated transmission fluid or low fluid level - Pour fresh fluid or add transmission fluid to proper level.
Defective or not adjusted speed control pedal linkage - Adjust or change linkage.
Relief valve failure - Replace the valve.
Excessive transmission load - Reduce transmission load.
Defective or worn transmission parts - Check hydrostatic transmission components for defect or damage and change if necessary.

Low power
Insufficient transmission fluid - Check and refill the transmission fluid.
Relief valve failure - Replace relief valve as required.
Speed control linkage is worn or unadjusted - Adjust or install new linkage.

Transmission fluid overheated
Low fluid level - Need to add transmission fluid.
Clogged transmission fluid filter - Service or change transmission fluid filter.
Cooling components are damaged or clogged - Inspect all cooling components and service or replace if necessary.
Transmission is under excessive load - Load needs to be reduced.

Transmission oil leakage
Worn seals or gaskets - Seals and gaskets need to be replaced.
Transmission case internal pressure is too high - Change defective components.
Plugged transmission fluid return tube - Service or replace return tube.

Hydraulics Troubleshooting

Hydraulic system has overheating
Hydraulic pressure incorrectly adjusted - Correct adjustment is required.
Main relief valve failure or improper setting - Set up or change the relief valve.
Dirty hydraulic oil - The oil must be changed.
Not enough hydraulic oil in the system - Fill up the hydraulic oil.
Hydraulic pump is faulty - Repair or replace pump if necessary.

Boom won't lower or raise
Lift controls are damaged - Change or repair.
Hydraulic pump failure - Repair or replace pump if necessary.
Faulty hydraulic control valve - Repair or replace hydraulic valve.
Damaged hydraulic cylinder - Install a new boom cylinder or repair it.
Low hydraulic fluid level - Add fluid as required.

Bucket tilt does not work
Faulty bucket tilt controls - Repair or change.
Hydraulic pump not working - Repair or install new hydraulic pump.
Defective hydraulic control valve - Repair or replace the valve.
Damaged bucket cylinder - Repair or change cylinder.
Hydraulic fluid level low - Fill the system to proper hydraulic fluid level.

Slow boom or bucket operation
Worn hydraulic oil pump - Check pump performance and change it if necessary.
Leaking hydraulic cylinder - Replace cylinder piston seals.
Low hydraulic oil level - Check and refill the hydraulic oil.
Faulty or incorrect setting hydraulic control valve - Adjust correctly or repair.
Hydraulic system loosing pressure - Adjust pressure as required.

Bucket or boom is working jerkily
Air in hydraulic system - Need to bleed air.
Hydraulic oil filter is dirty - Clean or install new filter.
Hydraulic fluid contamination - Fill up with fresh hydraulic fluid.
Cylinder rod or tube is scratched - Replace defective component.

Excessive hydraulic pump noise
Hydraulic leaks or low oil level - Refill hydraulic oil or repair leaks in system.
Plugged hydraulic filter - Replace or clean the filter.
Clogged suction line - Suction line must be serviced.
Pump is sucking air - Bleed air.
Pump parts are faulty - Change or rebuild pump.

Electrical Troubleshooting

Battery does not charge
Loose or corroded electrical wiring connections - Service or tighten connections.
Faulty battery terminal clamps - Terminal clamps should be changed.
Worn-out battery - Battery replacement required.
Belt is defective or loose - Adjust belt tension or install a new belt.

Starter motor cranks slow
Low battery capacity - Recharge the battery.
Battery won’t hold charge - Service battery or change it.
Disconnected wires or corroded battery terminals - Check cables and service or change terminals.

Starter doesn't crank
Battery is low or faulty - Charge or change the battery.
Battery cables are disconnected or improperly connected - Inspect cables and connect properly.
Low battery power - Battery needs to be recharged.
Damaged starter motor - Starter needs to be replaced.

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WHEEL LOADERS SPECIFICATIONS

Caterpillar